Skyrmions go for a ride

Some physicists have high hopes that tiny vortices of magnetization called magnetic skyrmions will change the way we store data on computers. But there aren’t many materials that support those swirls of magnetism, and the ones that do require cryogenic temperatures. Now a research team led by Geoffrey Beach of MIT and Mathias Kläui of the University of Mainz in Germany has created and manipulated room-temperature skyrmions at the interface between metallic thin films. Using a technique for fabricating read and write heads for hard drives, the scientists sandwiched a thin sheet of cobalt or cobalt-iron-boron between two layers of nonmagnetic material, such as platinum or tantalum. Then they applied magnetic field pulses that caused the magnetic moments of interfacial atoms to twist and form skyrmions that were about 100 nm in diameter. The physicists next built a nanosized track and used pulses of current to push and pull the magnetic swirls at speeds exceeding 100 m/s. The track demonstration is significant because it is modeled after the workings of a proposed data storage device called racetrack memory. Physicists envision skyrmions as robust data carriers—the state of a bit would be determined by the presence or absence of a skyrmion—that are smaller and could be manipulated far more quickly than the magnetic domains in traditional hard drives. The next step toward that goal is generating skyrmions that don’t require a bulky or energy-sapping external magnet to maintain stability. (S. Woo et al., Nat. Mater., in press, doi:10.1038/nmat4593 .)